Geology Reference
In-Depth Information
Beta decay: Beta decay describes when a neutron splits itself into two separate
particles — an electron and a proton — and the electron leaves that atom. The
result is that there is an additional proton in the nucleus, which changes the atom-
ic number and transforms the atom into a new element. For example, the isotope
potassium-40 (with an atomic number of 19) becomes calcium-40 (with an atomic
number of 20). The atomic mass number of these two atoms is the same, 40, be-
cause one neutron was replaced by one proton in the nucleus by the process of
beta decay. Beta decay is illustrated in Figure 16-5.
Figure 16-4: Alpha
decay of a radio-
active isotope.
Figure 16-5: Beta
decay of an iso-
tope.
Beta capture: Beta capture is the reverse of beta decay. In beta capture, an atom
grabs an electron from somewhere else and combines it with a proton to create a
neutron in its nucleus. The result is a change in the atomic number but not the
atomic mass number. For example, when potassium-40 (with an atomic number of
19) experiences beta capture, it becomes argon-40 with an atomic number of 18
because one proton from the nucleus of the potassium-40 atom has been com-
bined with the electron to create the new neutron. Beta capture is illustrated in
Figure 16-6.
Figure 16-6: Beta
capture of an iso-
tope.
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